Recent research and development efforts in the field of next generation wireless communication systems aim at providing much higher data rates than existing systems. For wireless devices and systems to communicate at a much higher data rate, better mechanisms are needed to perform initial time and frequency synchronization, cell identification, and channel estimation. Generally, reference signals or pilot symbols are used to provide such mechanisms.
A reference signal or pilot symbol refers to a known signal sequence inserted at a known location (time or frequency) of a data stream such that communication devices can easily detect the reference signal or pilot symbol, and perform time and frequency synchronization, to measure channel information, to perform interference mitigation or cancellation, etc., and/or to provide time/frequency offset estimation based on detected reference signal or pilot symbol.
Further, the next generation wireless systems may use orthogonal frequency division multiplexing (OFDM) techniques. An OFDM scheme uses different frequency bands, called sub-carriers, to transmit signals in parallel. Pilot symbols may be used in the OFDM scheme to provide not only channel estimation and time and frequency synchronization, but also to prevent frequency and phase shift errors of the sub-carriers.
For example, for IEEE (Institute of Electrical and Electronics Engineering) 802.16 Broadband Wireless Access Working Group, the pilot structure for documentation 802.16m is initialized in IEEE meeting #54. Although several design considerations for pilot structures have been discussed, currently there lacks a systematic approach to design pilot structures or patterns used in the next generation wireless communication systems.
Methods and systems consistent with certain features of the disclosed embodiments address one or more of the problems set forth above.